1. Field of the Invention
The present invention relates to a stent. More particularly, it relates a low profile highly expandable stent.
2. Description of the Prior Art
Stents for use in transluminal implantation are known in the prior art. Most are known to be balloon expandable, self-expandable, or thermally expandable. But, the degree of expansion in these prior art stents are determined by the diameter of the balloon used to cause the expansion or of the diameter of an artery when using self-expanding or thermally expanding means. An improved stent is needed in which the degree of expansion in the stent is not constrained by diameter of the balloon or of the artery.
Some prior art stents are known to comprise rigid and flexible portions. U.S. Pat. No. 5,383,892 ('892) to Cardon et al. disclose a stent employing at least two cylindrical rigid parts and at least one flexible part where the flexible part is welded to the rigid parts. Such a stent could be considered a combination stent utilizing a graft or other material. The invention of '892 is adapted such that the rigid parts expand radially in a plastic manner and flexible parts expand radially in an elastic manner. Unfortunately, the degree of expansion of the '892 stent is determined by the balloon used to expand the stent or the elastic nature of the metal used on the rigid parts. Such prior art stents are very limited in their degree of expansion and are not capable of the high degree of expansion seen in the stent of the present invention. In such a stent, it is necessary to form the stent having a very large profile, so that the higher degree of expansion can be achieved. However, large profile stents are not desirable due to the fact that they can not be used in minimally evasive surgical procedures. Requiring large incisions in the body and the artery only acts to complicate the surgical procedure and adds additional risk to the patient.
An improved stent is needed that utilizes combination stent-graft techniques and is capable of a high degree of expansion, yet retain a low profile so that surgeons can perform minimally evasive surgical procedures and use such novel stent in a wide range of artery diameters. Such improved stent can be manufactured in one size, yet be used universally.